A conventional domestic fan typically includes a set of blades or vanes mounted for rotation about an axis, and drive apparatus for rotating the set of blades to generate an air flow. The movement and circulation of the air flow creates a ‘wind chill’ or breeze and, as a result, the user experiences a cooling effect as heat is dissipated through convection and evaporation. The blades are generated located within a cage which allows an air flow to pass through the housing while preventing users from coming into contact with the rotating blades during use of the fan.
WO 2009/030879 describes a fan assembly which does not use caged blades to project air from the fan assembly. Instead, the fan assembly comprises a cylindrical base which houses a motor-driven impeller for drawing a primary air flow into the base, and an annular nozzle connected to the base and comprising an annular air outlet through which the primary air flow is emitted from the fan. The nozzle defines a central opening through which air in the local environment of the fan assembly is drawn by the primary air flow emitted from the mouth, amplifying the primary air flow.
Our co-pending patent application PCT/GB2010/050270 also describes such a fan assembly. Within the base, the impeller is located within an impeller housing, and the motor for driving the impeller is located within a motor bucket which is mounted on the impeller housing. The impeller housing is supported within the base by a plurality of angularly spaced supports. Each support is, in turn, mounted on a respective support surface extending radially inwardly from the inner surface of the base. In order to provide an air tight seal between the impeller housing and the base, a lip seal is located on the outer surface of the impeller housing for engaging the inner surface of the base.